Olympus Corporation and Nippon Sheet Glass Co. were under a Joint Research Agreement in effect prior to the date the invention was made and was made as a result of activity undertaken within the scope of the Joint Research Agreement.
1. Field of the Invention
The present invention relates to a processing method for glass substrate for forming a relief on the surface of glass substrate, a processed glass product obtained by the processing method, and a stress applying apparatus which applies stress to the surface of glass substrate.
2. Description of Related Art
Conventionally, there have been various processing methods for glass substrate for forming a relief on the surface of the glass substrate. As an example, a method has been proposed wherein, in order to deal with the recent demand for even higher densification of disks in the field of HDDs (hard disk drives), with the object of forming surface projections having an even height in desired positions on amorphous material (glass), a predetermined pressure force is applied to parts of the surface of the amorphous material to form a densified compressed layer. Then the outer layer is removed using processing agents with different removal capability depending on this compressed layer and other non-compressed layers, so that the compressed layer can be processed into a projecting shape (see Japanese Laid-open Paten Publication JP-2002-160943-A).
Incidentally, similarly to the processing method proposed in the above patent document, in a processing method wherein an external force is applied onto a glass substrate to form the compressed layer so that a relief is formed on the surface of the glass substrate utilizing the difference in etching rate between the compressed layer and non-compressed layer, the condition is required such that the glass substrate is not cracked when forming the compressed layer.